Tiling straight onto wood
If tiling onto existing boards of plywood, check that they’re fully supported by joists or noggings. Any damaged boards should be replaced, and noggings should be fitted between joists underneath any unsupported edges.
Boards should be screwed to the joists or noggings every 200-300mm, and there should be a 2mm allowance for expansion. The back and edges of the plywood should be primed with weber PR360, and the gaps willed with weberjoint silicone, to prevent them getting filled with tile adhesive later on.
Boards should be exterior grade, and at least 18mm thick. If the floor needs to support heavy loads, or if the joists are spaced more widely than normal however, an additional layer may be required to increase thickness and stability.
Fixing the tiles
Once the surface is ready, it’s time to start tiling. Tiles should be fixed into a solid bed of a flexible tile adhesive such as weberset rapid SPF, leaving joints at least 3mm wide to allow for grouting and movement.
The adhesive should be at least 3mm thick for over-boarding, and 5mm thick when tiling straight onto wooden flooring – it may need to be applied to the back of the tiles in order to reach this thickness. The adhesive should be spread evenly using a notched trowel at a constant angle.
The adhesive should be applied to areas of roughly 1m2 at a time, or as large an area as can be tiled within 10 minutes. Use a slight twisting motion and consistent amount of force when placing the tiles, which will help to ensure they’re stuck down firmly and evenly.
The adhesive should be left to set for at least 2 hours, and then the joints filled between tiles with a water-repellent and mould-resistant tile grout such as weberjoint premium to prevent mould and staining. Finally, use a colour-matched weberjoint silicone to fill movement joints at the edges of the tiled area.